Overbased barium additive and fuel oil composition

ABSTRACT

A PROCESS FOR PREPARING OVERBASED BARIUM HYDROCARBON SULFONATE FEATURING THE USE OF BARIUM SULFIDE AS THE BARIUM SOURCE. THE PRODUCT OBTAINED FROM THIS PROCESS AND DIESEL FUEL CONTAINING A SMOKE REDUCING QUANTITY OF THIS PRODUCT ARE DESCRIBED.

United States Patent Office Patented Sept. 26, 1972 3,694,175 OVERBASEDBARIUM ADDITIVE AND FUEL OIL COMPOSITION Charles E. Marble, Troy, Mich.,assignor to Ethyl Corporation, New York, N.Y. No Drawing. Filed Sept.16,1968, Ser. No. 762,369 Int. Cl. C101 1/32; C10m 1/40 US. Cl. 44-51 10Claims ABSTRACT OF THE DISCLOSURE A process for preparing overbasedbarium hydrocarbon sulfonate featuring the use of barium sulfide as thebarium source. The product obtained from this process and diesel fuelcontaining a smoke reducing quantity of this product are described.

BACKGROUND OF THE INVENTION This invention is directed to a method ofpreparing overbased barium sulfonates and their use in distillate fuels.

Processes for preparing overbased alkaline earth oil soluble sulfonatesare available in the art (see e.g. US. 2,617,049, US. 2,956,018, US.3,027,325, and US. 3,- 312,618). The principal products disclosed in theart appear to be those prepared from petroleum derived sulfonic acids.These petroleum derived sulfonic acids are in general alkaryl sulfonatesobtained as side products from the sulfuric acid treatment of petroleumhydrocarbons in refining operations.

The term overbased indicates that the resultant product from thesevarious processes contains an amount of alkaline earth metal greaterthan the stoichiometric amount of metal which would be present if theparticular sulfonic acid were fully neutralized. The theory of thisoverbased complex formation is not fully understood. One suggestion hasbeen that the oil soluble sulfonates act as protective colloids ordispersants thus keeping an alkaline earth compound suspended in a fiuidcarrier.

A general method of preparing these complexes features the in situformation of a finely divided alkaline earth compound such as CaCO inthe presence of a petroleum sulfonate in a hydrocarbon medium. This isaccomplished by introducing an acidic gas such as carbon dioxide into analkaline earth containing, petroleum sulfonate dispersion in ahydrocarbon medium. Recent improvements in this process feature the useof promoters such as low molecular Weight alcohols, phenols, amines, andthe like.

The present invention provides a method of preparing overbased bariumsulfonates featuring the use of barium sulfide as the barium source. Theproducts are elfective smoke suppressors in diesel fuels.

SUMMARY OF THE INVENTION A process for preparing overbased bariumsulfonates from a sulfonic acid material, barium sulfide, and carbondioxide in the presence of C -C alkanol and water in a hydrocarbonmedium; the product obtained by this process and its use as a smokereducing diesel fuel additive.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of thisinvention is a process for preparing an overbased barium sulfonate whichcomprises:

(1) preparing a slurry of barium sulfide in from about 100 to about 800parts by weight of C -C alkanol per mole of barium sulfide, adding atleast an equimolar amount of water based on barium sulfide, and heatingsaid mixture to a temperature from about 50 C. to the refluxtemperature,

(2) adding thereto a mixture of an inert hydrocarbon medium and asulfonic acid material selected from:

(a) G -C alkyl benzene sulfonic acids, and

(b) sulfonated olefin derivatives prepared by sulfonating mixtures ofacyclic, monoolefins having from about 14 to about 30 carbon atoms,

such that the molar ratio of barium sulfide to said sulfonic acidmaterial is from about 1:1 to about 10:1, (3) introducing carbon dioxidegas into the heated mixture of Step (2) until substantially no hydrogensulfide is evolved from said mixture, and (4) distilling said alkanoland water from said mixture.

Another preferred embodiment of this process features the use ofsulfonated olefin derivatives prepared by sulfonating a C olefin Whosespecific composition is given below. Dodecyl benzene sulfonic acid isused in a most preferred embodiment. Barium sulfide in the crude formknown as black ash is a most preferred form of BaS.

Sulfonic acid materials of various types may be used in the presentprocess. These include alkenyl sulfonic acids, alkyl sulfonic acids,hydroxy alkyl sulfonic acids, sultones, mixtures thereof, as Well asalkyl benzene sulfonic acid. Hydrocarbon soluble petroleum sulfonicacids, the socalled mahogany" sulfonic acids, are also useful in thisprocess. These mahogany sulfonic acids are mixtures of sulfonic acidsobtained during sulfuric acid treatment of petroleum refinery streams.

Sulfonic acid containing products obtained on sulfonating olefins areanother type of useful sulfonic acid material. These products arereferred to herein as sulfonated olefin derivatives. By olefins I meanhydrocarbon olefins. The products obtained on sulfonating acyclicmonoolefins having from about 14 to about 30 carbon atoms areparticularly useful. Especially useful olefin starting materials are themixtures of acyclic olefins obtained from synthetic manufacturingprocesses such as dehydrogenation of parafiins or polymerization of lowmolecular weight olefins such as ethylene and propylene. Syntheticallyprepared monoolefins having the following olefin makeup andconfigurations (double bond position) are most preferred; the olefinsare predominantly alpha. These mixed olefins are identified herein as Colefins.

Olefin chain length: Percent by weight 1 C and lower 0-3 C 0.5-17 C33-52 C 19-37 C 9-15 C 2-7 25+ 08 1 Vapor phase chromatography analysis.

Olefin configurations Percent distribution Vinyl 32-54 Internal 12-31Vinylidene 32-47 Nuclear magnetic resonance analysis.

In sulfonating olefins,, any suitable sulfonation procedure may beutilized. Suitable procedures are described in the following patents:US. 3,259,645; U.S. 3,337,437; British 1,072,601; French 1,403,407 andFrench 1,399,570. In general, the sulfonation of olefins comprisestreating olefins with a sulfonating agent such as S0 to produce asulfonated derivative.

The mixtures of useful ole-fins contain varying ratios and combinationsof olefins having from about 14 to about 30 carbon atoms. These mixturesmay contain linear olefins, branched olefins, and mixtures thereof.

Representative examples of monoolefin mixtures from which preferredsulfonated olefin derivatives are prepared are presented in thefollowing table; the mixtures contain more than about 60 percenta-olefins.

Blends of these mixtures are also useful. A blend of seven volumes ofmixture A and eleven volumes of mixture B is a particularly usefulblend.

Especially useful olefin sulfonation processes and the mechanismsinvolved are described in the journal Hydrocarbon Processing, vol. 47,No. 3, pages 109-114, March 1968. The material therein described isincorporated by reference. When sulfonating olefins, the productsobtained may be mixtures containing alkenyl sulfonic acids, hydroxyalkyl(or -alkenyl) sulfonic acids, and 5 and 6 membered ring inner esterscalled sultones. These sultones may comprise as high as 50 percent ofthe sulfonated olefin product when using a falling film reactor system.The sultones are readily saponified by treatment with a strong base.Thus, when sulfonated ole-fin products are used as the hydrocarbonsulfonic acid material in the present process, it is desirable tosaponify this product so that the full sulfonic acid value of thematerial is realized in the process. The saponification can be carriedout prior to the overbasing step in the process. By overbasing step ismeant the point at which carbon dioxide is introduced into the reactionmixture to form barium carbonate in situ. This saponification can becarried out by treating the sulfonated olefin product with a strong basesuch as sodium hydroxide or potassium hydroxide and heating to anelevated temperature for a few minutes. This saponification would yieldthe sodium or potassium salt of all the sulfonic acids present. It wouldbe better then to convert this salt to the corresponding barium salt foruse in the present process.

A more preferred procedure is to saponify the sultone containingsulfonated olefin derivative with barium oxide or barium sulfide/wateras the first step in the process and then to continue with theoverbasing step.

A most preferred Way of saponifying the sultone is to charge thesulfonated olefin derivative, the hydrocarbon medium, and the bariumsulfide-water-alcohol ingredients into the reactor and then heat thismixture to effect the saponification while bubbling the carbon dioxidethrough the mixture. This saponification step is an important feature ofthe process when sulfonated olefin derivatives which may containsultones are used as a starting material.

Alkylbenzene sulfonic acids wherein the alkyl group has 12 to 17 carbonatoms are also useful. Laurylbenzene sulfonic acid, heptadecylbenzenesulfonic acid, hexadecylbenzene sulfonic acid, tetradecylbenzenesulfonic acid and the like are examples of useful sulfonic acids. Mixedalkylbenzene sulfonic acids prepared for example from the hydrocarbonproduct of the Friedel Crafts alkylation of benzene with an olefincontaining principally tetrapropylene, are another example of a usefulsulfonic acid. The useful alkyl benzene sulfonic acids are alsocharacterized by having a molecular weight of less than about 400.

Dodecylbenzene sulfonic acid is an especially preferred alkylbenzenesulfonic acid.

Barium sulfide is the reactant utilized in the present process to supplythe barium values for the overbased.

product. A preferred form of barium sulfide is a crude product obtainedin the commercial preparation of barium sulfide by reducing a bariumsulfate 1 with carbon. This crude product is commonly called black ash;it contains up to about percent barium sulfide.

Typical analysis of commercial black ash is as follows; all percentagesare by weight.

Black ash typical analysis Percent Assay BaS 71.2-88.0 Insolublematerial 19.2-10.4 Calcium and strontium (as oxides) 0.5 Silica 0.4Aluminum and iron (as oxides) 1.5 Carbon 3.7 Magnesium (as oxide) 0.22.8

Thio and other reducible sulfur compounds The reaction of the presentprocess is carried out in a suitable hydrocarbon medium. The medium ischaracterized by being (1) inert during the process of the reaction and(2) a solvent for the sulfonic acid starting material. It is alsopreferred that this medium be a solvent for the overbased product whichis obtained in the process; and this hydrocarbon medium should becompatible with diesel fuel. Any hydrocarbon which meets these criteriamay be used. Aromatic hydrocarbons, parafiinic hydrocarbons, olefinichydrocarbons, mixtures thereof, light distillate hydrocarbon oils,distillate fuels, kerosene, straight run naphtha, petroleum refinerystreams such as catalytic reformate, thermally or catalytically crackedstreams, alkylated refinery streams, catalytically cracked naphtha andthe like, are useful hydrocarbon media. Benzene, C -C alkylbenzenes suchas toluene, xylene, actylbenzene, pentylbenzene and the like, (I -Cparaflins such as hexane, heptane, dodecane and the like, aviationalkylate, light processing oils such as No. 9 oil and the like,catalytic reformate containing over about 70 percent aromatichydrocarbons and the like, and mixtures thereof are some examples ofuseful media.

The amount of hydrocarbon medium used in the process is not critical. Anamount of inert hydrocarbon ranging from about 0.5 to about 10 times theWeight of the sulfonic acid material can be used.

Alkanols having from about 1 to about 5 carbon atoms are used in thepresent process. The exact function of the alkanol used in the processis not understood; however, the alkanol is required in order for thereaction of the present process to be carried out. Examples of usefulalkanols are ethanol, isopropanol, pentanol-3, amyl alcohol, butylalcohol, and mixtures of these alcohols. Methanol is a most preferredalkanol.

The amount of alkanol used may be varied. Generally the barium sulfidereactant is dispersed in the alkanol as an initial step. The amount ofalkanol used is based on the amount of barium sulfide used. Thus,amounts of alkanol ranging from about to about 400 parts by weight permole (167 parts by weight) of barium sulfide are generally used.

Water is also required in the present process. At least an equimolaramount of water based on the barium sulfide used is necessary. A largeramount of water, for example up to 2 times the necessary amount, canalso be used. The water (and alkanol) has to be distilled off as a finalstep in the process. As a practical matter then, too large an excess ofwater is not used.

The amount of barium sulfide used in the present process must be morethan the stoichiometric amount required to neutralize the sulfonic acidsupplied by the sulfonic acid material. One mole of barium sulfide willneutralize two moles of a sulfonic acid. Thus, the stoichiometricrelationship in moles of sulfonic acid to moles of barium 1 A Bills odore is used.

sulfide is 2:1. Since the product obtained in the present process isoverbased, that is, contains more than the stoichiometric amount ofbarium, a. greater than stoichiometric amount of barium sulfide must beused in carrying out this process. Molar ratios of sulfonic acid tobarium sulfide of from 1:1 up to about 1:10 can be used. Ratios of fromabout 1:2 to about 1:5 are preferred.

The process is carried out at elevated temperatures. Reactiontemperatures ranging from about 50 C. up to the reflux temperature ofthe reaction mixture are used. The reflux temperature, of course, willbe dependent upon the particular hydrocarbon medium used, its amount,and the amount of alkanol and water in the reaction mixture. An uppertemperature limit would be about 150 C. This reaction temperature is thetemperature at which the carbon dioxide is passed into the solution toeffect formation of the overbased complex.

The mixture containing the sulfonic acid material in hydrocarbon medium,BaS, H 0, and alkanol is subjected to treatment with carbon dioxide gas;this is the overbasing step. The CO is simply bubbled through themixture at the aforesaid reaction temperatures until substantially no H8 gas is evolved from the mixture. At this point the reaction isconsidered complete. Any means of detecting the presence of H 8 in theefli-uent gas coming from the mixture can be used to determine thispoint; a convenient method is to test the efiluent gas with wet leadacetate paper. The treatment with CO effectively complexes thestiochiometric excess of barium sulfide (converted to barium carbonate)with the neutralized sulfonic acid, thus forming an overbased bariumsulfonate.

The process of this invention is ordinarily carried out at atmosphericpressures. However, it can also be carried out at pressure aboveatmospheric. The use of pressures above atmospheric can be used toadvantage to minimize solvent loss while carrying out the reaction;higher pressures might also be desirable when a reaction temperaturehigher than the reflux temperature is used to carry out the reaction.The following examples illustrate the process of the present invention;all parts are by weight unless otherwise indicated.

EXAMPLE 1 A vessel fitted with stirrer, thermometer, water collector,and condenser is charged with 100 parts (0.5 mole) of 85 percent assaybarium sulfide and 300 parts methanol. This slurry is stirred and about9 parts (0.5 mole) of water was added; the mixture was heated to 55-60C. and kept at this temperature for 50 minutes. A solution of 59.8 parts(0.2 mole) of dodecyl benzene sulfonic acid in about 220 parts of xylenewas added and the mixture was refluxed for 30 minutes (hydrogen sulfidewas evolved). A stream of carbon dioxide gas was then bubbled throughthe mixture until evolution of hydrogen sulfide had essentially stoppedhours). The methanol and water were then distilled from the mixture(about 44 parts of xylene containing about .8 part of dimethyl formamidewas added during the distillation). The mixture was cooled and thendiluted further with about 310 parts of benzene containing about .8 partof dimethyl formamide. The solution was then filtered twice and thebenzene and a portion of the xylene were distilled off under vacuum. Theproduct at this point gelled on cooling. The product was diluted againwith benzene (about 180 parts) and dimethyl formamide (about 2.5 parts).The solution was stirred and then the benzene was distilled off undervacuum. 229 parts of a slightly viscous, clear product were obtained.About 0.8 part of dimethyl formamide was added to the product to reduceits viscosity.

Analysis of the overbased barium sulfonate product showed that itcontained 23.6 percent barium and 2.4 percent sulfur.

EXAMPLE 2 Example 1 is repeated substituting 0.05 mole ofheptadecylbenzene sulfonic acid for the dodecylbenzene sulfonrc 6 acid,50 parts of isopropanol for the method and toluene for the xylene; thereaction mixture is heated to about 5 0 C. while the carbon dioxide isbubbled into it.

An overbased barium sulfonate product is obtained.

EXAMPLE 3 A vessel fitted with a stirrer, thermometer, water collector,and condenser was charged with 100 parts (0.5 mole) percent assay bariumsulfide and 300 parts of methanol. This suspension was stirred and about9 parts (0.5 mole) of water were added, followed by a solution of 59.8parts (0.2 mole) dodecylbenzene sulfonic acid in 75 parts pale oil (SunCirco )Q(X Lt) and 170 parts naphtha (aviation alkylate). This mixturewas refluxed for 30 minutes and then carbon dioxide was passed throughthe mixture for 5.5 hours. The methanol and water were then distilledoff; about 80 parts naphtha were added during this distillation period.The mixture was cooled and it was further diluted with about 270 partsof hexane. The solution was then filtered; the filtrate was stripped ofsolvents under vacuum. 224.3 parts of a very dark, slightly hazy viscousliquid product were obtained.

Analysis of this product showed it to contain 28.1 percent barium, 3.1percent sulfur.

Similar results are obtained when mahogany sulfonic acid is used inplace of the dodecyl benzene sulfonic acid. Using black ash to providean equivalent amount of barium sulfide also produces an analogousproduct. The reaction of Example 2 is carried out with similar resultswhen ethanol, isopropanol or amyl alcohol is used in place of themethanol. Similar results are obtained when the reaction in Example 3 iscarried out in benzene, kerosene, hexane, toluene, and a mixture of No.9 oil and xylene.

EXAMPLE 4 A vessel fitted with a stirrer, thermometer, water collectorand condenser is charged with parts (0.5 mole BaS) of black ash (84.5percent barium sulfide) about 400 parts methanol. About 9 parts (0.5mole) of water is added to the stirred slurry and the mixture is heatedto about 60 for about one hour. To this suspension is added a solutionof 97.4 parts (0.08 mole) of a sulfonated C olefin derivative in about450 parts of xylene; this mixture is then refluxed for about 30 minutes.Carbon dioxide gas is then bubbled through the mixture untilsubstantially no hydrogen sulfide is evolved from the reaction mixture(detectible by lead acetate paper). The methanol and water are distilledolf. The mixture is then diluted with about 400 parts of benzene. Thissolution is filtered. The product obtained is an overbased bariumsulfonate.

An analogous product is obtained when the process of Example 4 iscarried out under pressure at a temperature of C.

The sulfonated C olefin derivative used in Example 4 is a productobtained on sulfonating an olefin mixture having the general compositiondisclosed above. In order to determine the sulfonic acid content and thesultone content of this derivative, its acid number and itssaponification number are determined. The difference between thesaponification number and the acid number represents the amount ofsultone present in the sulfonated derivative. If a substantial portionof the product is sultone then a saponification step using barium oxideor barium sulfide and water as herein described may be used in carryingout the process of Example 4 more efiiciently.

The products of the process of this invention as illustrated by theexamples above, are especially useful as smoke reducing additives indiesel fuel. Another embodiment of this invention is a diesel fuelcontaining a smoke reducing quantity of a product made by the process ofthe present invention. The amount of such product added to a diesel fuelranges from about 0.05 percent by weight to about 3 percent by weight ofthe fuel.

The products obtained by the process of the present invention asillustrated in the above examples are especial- 1y useful as smokesuppressors in distillate hydrocarbon fuels used in diesel engines, andcan be added to any commercial diesel fuel. In general these fuels arecharacterized as having a boiling range of 350 F. to 700 F. So-calledresidual oils having higher boiling points than this are sometimesblended with a lower boiling diesel fuel. Suitable diesel fuel oils areFederal Specification VV-F800 Grades DF-A, DF-l, DF-2 and DF-4, as wellas ASTM Classes 1, 2, 3, and 4. Marine diesel fuel oils are also useful.A tabulation and discussion of suitable diesel fuel oils is presented inFuels and Lubricants, Milosh Popovich and Carl Hering, pages 134;146-151, John Wiley and Sons, Inc., New York (1959).

Following are examples of diesel fuel compositions of this invention.

EXAMPLE 5 A diesel fuel composition is prepared by adding 0.05 percentby weight of the product of Example 2 to a Class 1 diesel fuel oil.

EXAMPLE 6 A diesel fuel composition is prepared by adding 3 percent byweight of the product of Example 1 to Grade DF-3 diesel fuel oil.

EXAMPLE 7 A diesel fuel composition is prepared by adding 1.5 percent ofthe product of Example 3 to a Class 2 diesel fuel oli.

EXAMPLE 8 A diesel fuel composition is prepared by adding 0.2 percent byweight of the product of Example 4 to Grade DF-2 diesel fuel oil.

EXAMPLE 9 A diesel fuel composition is prepared by adding 0.6 percent byweight of the product of Example 2 to a marine grade diesel fuel oil.

The fuel compositions of the present invention produce less exhaustsmoke than the same base fuel containing none of the overbased bariumsulfonate products of the present invention. For example, noticeablyless smoke is emitted from a diesel engine when it is operating on thefuel composition of Example 6 than when it is operating on Grade DF-3diesel fuel containing no overbased barium product. Thus, the tendencyof a diesel engine to produce exhaust smoke is substantially reducedwhen a diesel fuel containing the overbased product prepared by theprocess herein described is used as a fuel.

The present invention therefore is encompassed in three embodiments,

(1) a process for preparing overbased barium sulfonate products, (2) theoverbased barium sulfonate product, and

,(3) diesel fuel containing a smoke reducing quantity of this product.

All three embodiments have been described in the foregoing disclosure;it is desired to limit this invention only within the spirit and scopeof the following claims.

I claim:

1. A process for preparing an overbased barium sulfonate whichcomprises:

(1) preparing a slurry of barium sulfide in from about 100 to about 800parts by weight of C -C alkanol per mole of barium sulfide, adding atleast an equimolar amount of water based on barium sulfide, and heatingsaid mixture to a temperature from about 50 C. to the refluxtemperature, 2. The process of claim 1 wherein said barium sulfidemedium and a sulfonic acid material selected from: '(a) C12-C17 alkylbenzene sulfonic acids, and

(b) sulfonated olefin derivatives prepared by sulfonating mixtures ofcyclic, monoolefins having from about 14 to about 30 carbon atoms, suchthat the molar ratio of barium sulfide to said sulfonic acid material isfrom about 1:1 to about 10: 1,

(3) introducing carbon dioxide gas into the heated mixture of Step (2)until substantially no hydrogen sulfide is evolved from said mixture,and

(4) distilling said alkanol and water from said mixture.

2. The process of claim 1 wherein said barium sulfide is a crude bariumsulfide.

3. The process of claim 1 wherein said sulfonic acid material is saidalkylbenzene sulfonic acid and wherein the said molar ratio of bariumsulfide to sulfonic acid is from 1:1 to about 5: 1.

4. The process of claim 1 wherein said sulfonic acid material is asulfonated olefin derivative prepared by sulfonating a mixture ofacyclic monoolefins comprising by weight 0-3% C and lower olefins 05-17%C olefins, 33-52% C olefins, 19-37% C olefins, 9-115 C olefins, 2-7% Colefins and 0-8% C and higher olefins and wherein the distribution ofolefin configurations in said mixture is 12-31% internal, 32-54% vinyland 32- 47% vinylidene, and wherein said ratio of barium sulfide to saidsulfonated olefin derivative is from 1:1 to about 5:1.

5. The process of claim 3 wherein said sulfonic acid is dodecyl benzenesulfonic acid, said hydrocarbon medium is selected from xylene, lighthydrocarbon oils, naphtha, aviation alkylate, and hexane, said alkanolis methanol and wherein the molar ratio of barium sulfide to dodecylbenzene sulfonic acid is about 2.5: 1.

6. The product prepared by the process of claim 1.

7. The product prepared by the process of claim 2.

8. A diesel fuel containing a smoke reducing quantity of the productprepared by the process of claim 1.

9. A diesel fuel containing a smoke reducing quantity of the productprepared by the process of claim 4.

10. A diesel fuel containing a smoke reducing quantity of the productprepared by the process of claim 5.

References Cited UNITED STATES PATENTS 2,695,910 11/1954 Asself et al25233 X 2,956,018 10/1960 Carlyle et al. 25218 3,021,280 2/ 1962 Carlyle25233 3,282,835 11/1966 Asseff 25233 X 3,312,618 4/1967 Le Suer et al.25233 3,437,465 4/ 1969 Le Suer 4451 FOREIGN PATENTS 661,907 2/1965Belgium 44-76 DANIEL E. WYMAN, Primary Examiner W. .T. SHINE, AssistantExaminer U.S. Cl. X.R. 44-76; 25233 *;g;;g V UNITED STATES PATENT OFFICECERTIFICATE OF CQRRECITION' Patent No. 3,694,175 a I Dated September 26,1 972 Infintoz-(I) Charles E. Marble Iris certifiedthat error appears inthoabove-ide'ntificd patent h and that said Letters Patent are herebycorrected as shown below f l,- Column 8, line 5 the correct phraseshould read (2) adding thereto a mixture of an inert hydrocarbon jinstead of as shown in the patent.

Claim 1, Column 8, line 9 "cyclic" should read e -acyclic .jClaim 4,Column 8, line 27 v' thecorreot ratio should read 9 15/o C instead of asshown in the patent.

Signed and sealed this 6th day of February 1973.

(SEAL) A-ttest:

EDWARD M.FL1:;TCHER,JR ROBERT GOT'ISCHALK Attestlng Officer Commissionerof Patents

